(1) Field of the Invention
This invention relates to the dispensing of fluids and is more particularly concerned with an apparatus and method for mixing two or more fluids and dispensing the mixture in a controlled manner.
(2) Description of the Prior Art
It is desirable to dispense fluid from a relatively inexpensive package which may be disposable after use or which may be recoverable for re-use. In some applications it is desirable to be able to mix fluids from two or more separate containers and then dispense the mixed fluids. This is particularly the case with two or more fluids which may be chemically reactive or unstable when stored in admixture for a prolonged period and which must be dispensed very soon after mixing. A typical situation is that posed by periodontal applications where it is desirable to mix two incompatible chemicals as disclosed in U.S. Pat. No. 4,521,403.
A typical device for dispensing fluids from a plurality of containers is disclosed in McCulloch, U.S. Pat. No. 3,613,956. The latter discloses two aerosol dispensing containers having hollow stems displaceable to discharge fluid under pressure. The actuating mechanism is a handle which pulls the valve stems inward toward their respective containers. The valves are manually pulled inwardly by a trigger which is returned to its original position when it is no longer desired to dispense fluid from the aerosol containers. One of the primary disadvantages of a system that contains aerosol valves that may be repeatedly opened and closed is that the fluid in the containers is not completely dispensed in one actuation of the valves. Since the pressures and the flow rates through the valves may differ from container to container depending upon the type of fluid being dispensed, the size of the valves, and the pressure in the container, the materials may be mixed in undesirable proportions. In addition, if the containers have equal pressures, but the flow rate through the respective valves is different, the head pressure in the mixing chamber may rise to a level where it prevents flow from one of the containers. Thus, the liquids will not be mixed in the desired proportions.
As well as the above disadvantages this type of device suffers the serious problem of bulk which requires the operator to utilize both hands in the dispensing mode. Thus, one hand has to be utilized to actuate and maintain liquid flow and the other hand is utilized to direct the liquid being dispensed to the locus to be treated.
It is accordingly highly desirable to provide a device which will not only mix and dispense fluids but which is of such size and mode of operation as to be held in one hand by an operator and to continue to dispense fluid to the locus to be treated at a controlled rate after actuation without further manual manipulation of the actuating mechanism.